1. Field of the Invention
This invention is in the field of refrigerant systems or heat pump systems. More particularly, it is a heat exchanger-accumulator that can be used as an evaporator on the suction side of a compressor for such a heat pump system.
2. Description of the Prior Art
In the prior art, each of the refrigerant or heat pump systems has had a piece of equipment to transfer heat to or from the refrigerant. Particularly in heat pump systems, heat is absorbed by the refrigerant by vaporizing the condensed liquid which then allows refrigerant to be taken into the compressor as a gas.
There have been many types of heat transfer systems for accomplishing this. For example, there have been systems for heat exchanging directly with ambient air such as air to air heat pumps. The problem with these systems during the heating mode is the formation of condensation followed by a freezing of the liquid condensate to block the air passageways on the evaporator surface. There have been employed also liquid-liquid heat pump systems in which liquids, such as water from wells penetrating the earth formations, were used as the heat source to vaporize the liquid refrigerant. These systems have employed expensive dual pipe arrangements in which an inner conduit was maintained concentrically within an outer conduit. As a consequence, there has been no place for the liquid refrigerant to separate from the general vapors and the vapors occupy heat transfer surface and serve to reduce heat transfer. This increased the expense of such equipment and has detrimental impact on system efficiency. Moreover, the pressure drop through such conventional tube-in-tube heat exchanges has hurt performance of the heat pump unit, particularly where such devices were connected in series flow path configuration as was the usual practice.
Typical of the prior art are the following articles and patents.
In the January, 1979 issue of "Air Conditioning and Refrigeration Business," there is an article entitled "Suction-line Accumulators for Heat Pumps;" Darwin R. Grahl.
Typical of the U.S. patents are the following: Nos. 3,242,679 shows a solar unit with pipes in the evaporator. 3,488,678 shows a u-pipe with a capillary in the bottom and with a separate inlet. 3,512,374 shows a suction accumulator with an inline intake-discharge. 3,563,053 shows a suction accumulator with similar tube arrangement to 3,488,678. 3,600,904 shows liquid level sensor in an accumulator. 3,609,990 shows a suction accumulator with a tube arrangement similar to 3,488,678. 3,765,192 shows an evaporator with a coil and a spray to spray liquid up on the coil with an exterior space around the coil for passage of the gas to the top outlet.
From the foregoing, it can be seen that none of the prior art approaches show the desirable feature of having the safety of an overflow chamber in an accumulator and having a properly sized unit with a vertical pressure vessel small enough to keep the refrigerant charge low and make more nearly universal and economically feasible the heat pump systems, especially multi-coil heat recovery sustems or solar assisted heat pumps.
Moreover, none of the prior art had the desirable feature that the unit can be employed to retro fit, or fit into an existing units, means to efficiently use supplemental heat sources to make economically feasible the heat pump units even in areas that did not have readily available solar energy, relatively high winter temperatures or the like.